<title>High-reliability high-performance optical data storage system architecture</title>

Abstract

With the terabyte demands of storage in many applications, the improvement of the speed of optical disk, especially the write performance will definitely extend the scope of their applications and enhance the overall performance of computer system. One effective way to improve the speed is to use a plurality of optical disk drivers together to construct an optical storage array similar to Redundant Arrays of Independent Disks (RAID). According to the typical architecture of RAID, the most common fault tolerant RAID architecture is RAID level 1 or RAID level 5. Both are not suitable for optical storage array because RAID level 1 architecture has the most redundancy, while the write performance of RAID level 5 architecture is one-fourth of that of RAID level 0 architecture especially for the small- write problem. In this paper, we propose a high performance and high reliability optical disk array architecture with less redundancy, called Mirror Striped Disk Array (MSDA). It is a novel solution to a small write problem for disk array. MSDA stores the original data in two ways, one in a single optical disk and the other in a plurality of optical disks in the way of RAID level 0. The redundancy of whole system is less than RAID level 1 architecture but with the same reliability as RAID level 5. As the performance of RAID level 0 part of optical storage system is much higher than that of RAID level 5 in ordinary disk array, thus it avoids the write performance loss when using Mirror Striped Disk Array architecture. Because it omits the parity generation procedure when writing the new data, thus the overall performance of Mirror Striped Disk Array is the same as that of RAID level 0 architecture. Using this architecture, we can achieve the high reliability and high performance optical storage system without adding any extra redundancy and without losing any performance compared with RAID level 0 architecture but with the reliability much higher than that of RAID level 5.